Piston regrooving tool



Aug. 28, 1951 c. M. WETZEL PISTON REGROOVING TOOL 2 Sheets-Sheet 1 Filed Oct. 25, 1946 FIG. 1-

Inventor CLARENCE M. WETZEL Attorneys 8, 5 c. M. WETZEL 2,566,048

PISTON REGROOVING TOOL Filed Oct. 25, 1946 2 Sheets-Sheet 2 FIG. 4

Inventor 5 CLARENCE M. WETZEL Patented Aug. 28, 1951 UNITED STATES PATENT OFFICE PISTON REGROOVING TOOL Clarence M. WetzelQIndianapolis, Ind., assignor to Perfect Circle Corporation,=Hagerstown, Ind., :a corporation of Indiana Application Octdber25, 1946, Serial No.705,723

'2Claims.

The present invention relates to hand tools in general, but is more particularly concerned with devices for recutting and reconditioning the ringreceiving grooves in-the pistons utilized in internal combustion engines and the like.

It is well known that one of the conditions that militates most seriously against satisfactoryperformance of piston rings over long periods is' the side wear in the ring grooves of the pistons. During the operation of the engin the grooves in the pistons become irregular and widened due to normal wear and impact of the piston rings against the sides thereof. This Wear is most pronounced in the ring groove adjacent to the head of the piston, which is commonly known as the top groove. In reconditioning pistons of engines that have been in operation for long periods of time it has been found that the wear is so great especially in the top groove of the pistons that the piston rings designed for the piston fit very loosely and, therefore, give poor service. Consequently, it usually becomes-necessary to regroove, in particular, thetop ring groove in the piston by remachining the groove'ina lathe to Widen the groove and accuratelyb'ring its side into tru parallelism. Ordinarily the groov is widened sufficiently to accommodate a piston ring of standard width and a steel segment or split ring, having a width of say approximately twenty-five thousandths (0.25") of an inch, though a ring'having any oversize of the same total dimension in width maybe employed. This operation takes considerable time and is difiicul t, even where good lathe equipment is available, because the piston must be accurately centered and trued before machining. Furthermore, many service stations, machine shops and garages, where engines are overhauled are not adequately equipped with a lathe or are without labor highly skilled in the operation 'oflathes.

It is therefore an object of the'present invention to provide a simple hand devic or tool which very accurately and eflicientlyregrooves'the worn ring grooves inpis'tons'to-th'e proper dimensions and which may be operated by unskilled labor.

It is a further objectof the present invention to provide a hand device 'havingadjustable elements whereby the devicemay'be utilized inregrooving pistons of diiferent "diameters as 'well as pistons having differently spaced .ring grooves therein.

It is another object of the invention to provide a hand device which utilizes 'one' of the groovesin the piston to guide the devic while another groove in the piston is being regroove'd.

It is still another object of the invention to provide a hand device which automatically feeds a cutting tool into one of the grooves in the pis ton as the device is manually rotated aroundthe piston as a unit.

It is also an object of the invention to provide a hand device which is rotated as a unit about the piston by a handle gripped by the operator, with connections between th handle and cutting tool for advancing the latter as an incident to the rotation of the device, the handle'being removableto permit rapid retractionof the tool 'by manipulation of the connections. I

Other objects and advantages of the invention will be apparent from the-following specification taken in connection with the accompanying drawings, in which:

Figure 1 is a plan View of a regrooving device embodying my invention;

Fig. 2 is a side view of the device, looking at the side which is at the bottom of Fig. 1';

Fig. 3 is'a'nother side view of the device looking at the side at the right hand of Fig. .1 and showing the handle thereof partially removed from the device;

Fig. 4 is a fragmentary vertical sectional view taken along line '4-4 of Fig. 1, and showingthe device'appliedto a piston; and l Fig. 5 is a fragmentary perspective view of one end of'a'modified locatingpin.

Referring now'to the drawings, it will be seen that'the body of the device consists of a substan-' tially circular body casting ill having a central opening of sufficient diameter to permit pistons of different diameters to be placed therein.

Equally spaced around the body casting H) are threerod-li'ke locating pins 1 I, I2 and 13 Which are adapted to register at their inner ends Ha, 12a and [3a in oneof the ring grooves of a piston and which are adjustably fastened in the body casting H3 by means of wing nuts l4, l5 and Hi. The inner ends Ila, 12a and 13a of the locating pins 1 l, 12 and I 3 are machined to slidablyfit between the sides of aring groove in a .piston, as is 'clearly illustrated-in Fig. 4 of the drawings. In order to accommodate pistons having ring grooves of .a different width,the opposite end *of the locating pins I I, 12 and 13 may be machined accordingly. If desired the ends of th locating pins may be oval or generally lozenge-shaped in transversescross section :as illustrated at 5| inFig. 5, thepin being rotatably adjusted so that the ends may accommodate piston grooves of several di'fierent'widths. #Each of thelocating pins H, l2 and l3 is'also .provided with pilot markings, such as indicated at ll, whereby the operator using the tool may readily determine when th piston is centrally located within the opening in the body casting l0.

Diametrically opposite the pin 1 I, the body casting in is provided with a dovetailed race H3 in which is mounted a slidable tool carriage 18. The width of the carriage I8 is somewhat narrower than the race and thus provides suflicient space to accommodate a gib member which is adjustably positioned by screws 2 I, whereby the side play between the carriage l8 and the race may be controlled. Nuts 22 are employed to lock the screws 2| in the selected position.

In order to control the advance and withdrawal of the carriage l8 along the slide race, one end of the carriage I8 is provided with a threaded hole 23 which accommodates a feed screw 24 having a collar 250.. A shaft portion 25 on the feed screw 24 extends through an appropriate opening or bearing in a gear support 26. The gear support 26 is fixedly supported on the body casting H] by means of the screws 2?. A worm gear 29 is rigidly secured to the outer end of the shaft portion 25. It is apparent that rotation of the worm gear 29 in one direction will feed the tool carriage [8 toward the center of the body casting l0 and that rotation of the worm gear 29 in the opposite direction will withdraw the tool carriage away from the center of the body casting 19.

Referring now to Fig. 4 of the drawings, it is noted that the inner end of the tool carriage I8 is provided with an adjustable cylindrical cutting tool holder 39. Substantially centrally located between the top and bottom of the tool holder 30 is an opening 3| into which the cutting tool 32 is inserted and secured in place by means of a set screw 32a. The opening 3! in the holder 30 maybe of any shape necessary to accommodate the cutting tool 32 but the preferred arrangement is to provide a square cutting tool 32 and opening 3|. With this arrangement the end of the carriage I8 is provided with a slot 33 which extends through to the wall of the cylindrical tool holder 30 and which is substantially the same width as the cutting tool 32. Consequently, the sides of the slot 33 provide additional side support for the end portion of the cutting tool 32 that extends beyond the peripheral edge of the tool holder 39. Furthermore, since the slot 33 extends through the end portion of the carriage Hi to the cylindrical surface of the tool holder 30, the tool holder 30 may be raised or lowered in the carriage [8 a substantial distance before the cutting tool 32 strikes either the upper or the lower inner edge of the slot 33.

In order to provide a simple but accurate means for adjusting the tool holder '30 vertically, the upwardly extending body portion of the carriage i8 is threaded to receive an adjusting screw 34 having a knurled hand knob 35 and a collar portion 36. This collar portion 36 extends into a groove 31 in the tool holder 39 so that rotation of the screw 34 by the hand knob 35 accurately adjusts the vertical position of the tool holder 30 and, consequently, the position of the cutting tool 32 with respect to a ring groove in a piston.

In order to lock the tool holder 30 in its adjusted vertical position, a lock screw 38, having a knurled hand knob 39, is threaded into the upwardly extending body portion 40 of the carriage l8 until the end thereof engages the body of the tool holder 39.

Finally, the regrooving device is provided with a removable handle 4| for rotating the device as 2.

unit around a piston which is to be regrooved. The handle comprises a knurled hand grip portion 42, a shank portion 43, a worm portion 44, and an end shank portion 45. In order to provide suitable bearing surfaces for the shank portion 43 and the end shank portion 45, the gear support 26 includes an upper socket member 46 and a-lower socket member 41, adapted to receive the shank portions 43 and 45 respectively.

In the operation of the regrooving device the body casting Ill is placed around a piston and the locating pins H, [2 and [3 are positioned into a ring groove of a piston so that the piston is located in the center of the body casting l0 and so that the ends Ha, l2a and [3a of the respective locating pins firmly, but sli'dably, engage the base of the ring groove below that which is to be remachined. The pilot markings IT on the locating pins II, [2 and [3 may be utilized by the operator as a guide to determine when the piston is properly centered. The wing nuts l4, l5 and I6 are then tightened. Assuming that the top groove in the piston is to be regrooved, the 10- cating pins ll, l2 and I3 are placed into the adjacent groove. With the device placed upon the piston in this manner, the operator may now rotate the worm gear 29 with his thumb in order radially to feed the tool carriage I8 until the cutting tool 32 barely clears the exterior surface of the piston. The operator now adjusts the vertical position of the cutting tool 32 by rotating the knob 35 on the screw 34 in the proper direction until the cutting tool 32 is positioned to cut an approximately equal amount of material from each side of the top groove of the piston. After the cutting tool 32 has been properly positioned, the knob 39 on the lock screw 38 is rotated to lock the cutting tool holder 30 in its adjusted position. The operator now slips the handle 4| into the socket members 46 and 41, with the worm 44 thereof in cooperative relationship with the worm gear 29, and, while firmly gripping the handle with one hand, rotates the entire tool assembly around the piston in a clockwise direction. The piston may be held against rotation by the operator grasping the attached connecting rod 50, or the latter may be held in a vise or other handy tool. It will be seen that as the handle 4! is firmly grasped and held against rotation about its own axis by the operator while the device is being rotated as a whole around the piston, the worm 44 turns the worm gear 29 on the feed screw 24. Thus the latter uniformly and continuously advances the tool carriage l8 and the cutting tool 32 into the top ring groove of the piston. It has been found that excellent results may be obtained if the worm 44, the worm gear 29 and the feed screw 24 are so designed that each revolution of the device around a piston advances the cutting tool 32 approximately three thousandths (.003") of an inch.

In order to provide a final even finishing cut when the cutting tool reaches the base of the groove, the handle 4! is removed from the tool and the tool is then rotated around the piston one or more times, without advancing the cuttingtool 32. The cutting tool 32 may now be retracted rapidly by hand spinning the worm gear 29 in the proper direction. The regrooving operation is now complete and the device may be quickly removed from the piston by merely loosening the wing nut I4 and retracting the locating pin H diametrically opposite the carriage l8. Since the adjustment of the remaining locating pins l2 and I3 has not been altered, the tool may be quickly centered on another piston of the same size.

While one embodiment of the invention has been disclosed, it will be understood that various modifications may be made therein which are within the true spirit and scope of the invention.

I claim:

1. A device for regrooving pistons comprising a body member for rotatably supporting the device on a piston, a tool carriage slidably mounted on said body member, a cutting tool at one end of said carriage and a feed screw threaded into the opposite end thereof, a handle extending into said body member adjacent said opposite end of said tool carriage for rotating the device as a unit, said handle having a pair of spaced trunnion portions at its inner end and said body member having a pair of cooperating sockets for rotatably receiving said trunnion portions, and operating connections between said handle and said feed screw including a worm on said handle intermediate said trunnion portions and a worm gear connected to the outer end of said feed screw in operative engagement with said worm for effecting movement of said carriage radially of the piston in response to rotation of the device by means of said handle.

2. A device for regrooving pistons comprising an annular body member adaptedto receive a piston, a cutting tool movably carried on said body member, means for effecting movement of said cutting tool radially of the piston in response to rotation of the device about the piston, and a plurality of radially extending guide pins carried by said body member and adapted to extend into engagement with a ring groove of the piston for supporting the device thereon, said pins being rotatably adjustable about their axes and having their inner ends generally lozenge-shaped in transverse cross section whereby the pins may be operatively received within ring grooves of varying width by adjusting the angular position of the pins.

CLARENCE M. WETZEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,848,418 Fall Mar. 8, 1932 1,915,350 Anderson June 27, 1933 2,399,309 Anderson Apr. 30, 1946 2,409,158 Simpson Oct. 8, 1946 

